Radiant energy device



I ma an Oct. 27, 1959 I w. F. HODGE 2,910,605

RADIANT ENERGYDEVICE Filed June 23, 1958 lrwven tov:

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United States Patet RADIANT ENERGY DEVIE William F. Hodge, Lyndhurst, Ohio, assignor to General Electric Company, a corporation of New York Application June 23, 1958, Serial No. 743,692

3 Claims. (Cl. 313-113) My invention relates to electrical radiant energy devices or lamps comprising an elongated tubular envelope having an incandescible filament extending longitudinally thereof for emitting infrared or visible radiations.

In certain applications, elongated tubular lamps are mounted in concave trough-shaped reflectors of heat or light-concentrating contour, for instance of elliptical cross section, with the filament extending along a focal line of the refiector to concentrate the heat or light at the other focal line. In accordance with the present invention, the lamp and reflector are combined in a single unit by properly shaping the glass or quartz lamp envelope to provide a reflector section and a transparent window section, the reflector section preferably being provided with a reflecting coating on either its inner or outer surface.

Itis a particular object of the present invention to providea novel filament supporting structure which will maintain the filament accurately at the focus of the reflector section. It is a further object to provide a supporting structure having a minimum shielding or shadowing effeet on the radiations emitted by the lamp. For a further understanding of the invention, reference may be had to the following detailed description taken in conjunction with the drawing wherein:

Fig. 1 is a front elevation of a lamp device comprising my invention;

Fig. 2 is a side elevation, in cross section, showing the envelope shape and one of a plurality of filament supporting members;

Fig. 3 is a perspective view, on an enlarged scale, of a filament supporting member;

Fig. 4 is an elevation showing a modified form of filament support; and

Fig. 5 is a view similar to Fig. 2 showing a further modified support member.

Referring to Fig. 1 of the drawing, the lamp illustrated therein may be generally of the type described and claimed in application Serial No. 376,042, A. G. Foote et al., filed August 24, 1953, now Patent No. 2,864,025 and assigned to the same assignee as the present invention. The lamp comprises an elongated tubular envelope 1 of radiation-pervious material such as glass or quartz, preferably cotaining a filling of inert gas, such as argon, and a longitudinally extending filament 2 preferably of coiled tungsten wire. The filament is mechanically and electrically connected at each end to a lead-in conductor 3 which extends outwardly through, and is hermetically sealed in, a flattened pinch or press portion 4 at each end of the envelope. When the envelope 1 is of quartz, the lead wires 3 may be of molybdenum with ribbon-like flattened intermediate sections 5 rolled therein as disclosed and claimed in Patent 2,667,595, Noel et al., or the section 5 may be a separate length of molybdenum foil welded to wire sections at each end, as is well known in the art.

In accordance with the invention, the envelope 1 is shaped to provide a concave trough-shaped reflector section 6 (Fig. 2) and an opposed flattened window section 7. The reflector section 6 is provided with a suitable reflecting coating on either its interior or exterior surface, here indicated by dotted lines at 8 as an external coating. When the lamp is designed to emit infrared radiations, the coating'S may be of gold. As shown in Fig. 2, the reflector section 6 is of elliptical cross section with major and minor axes 9 and 10, respectively. The filament 2 is located at one focus P1 of the ellipse and its image is at the other focus F2. The focus F1 is preferably as close as possible to the quartz envelope without overheating the quartz; the focus F2 is also located as close as possible to the window portion 7 of the envelope so that the elliptical reflector portion 6 will entercept as large as possible a fraction of the radiant energy from the filament 2. While the window portion 7 might be made flat or planar, it is preferably slightly rounded to avoid sharp angles which might weaken the envelope.

The filament 2 is supported accurately in the focal line F1 at spaced intervals along its length by support membars 11 which are attached to the filament so as to lie in planes perpendicular to the axis of the filament, and which also preferably occupy a minor portion of the crosssectional area of the envelope. It has been found that when the supports 11 are disc or wafer-like members occupying a large part or all of the cross-sectional area of the envelope, the interception thereby of radiation emitted from the filament 2 at angles directed toward the discs or wafers causes a shadowing effect; this is disadvantageous when, for example, the lamp is employed in a copying machine for printed matter where the shadowing effect results in underdeveloped or light narrow paths along the copy where it passes under the portions of the lamp occupied by the filament supports.

The above-stated objectives are fulfilled by the sup ports shown in Figs. 2 and 3 and comprising a Waferlike portion 12 of sheet metal secured to the filament 2 and having a portion 13 of its periphery shaped to the same contour as the apex of the reflector section 6 of the envelope, and also having a brace portion comprising finger-like extensions 14 extending to the internal shoulders 15 formed by the juncture of the reflector and window sections 6 and 7, respectively, of the envelope. In this case, the fingers 14 are part of a Wire member of modified U" shape having a base portion 16 joining the ends of the finger portions 14. The wafer portion 12 and wire portionsv M-l6 of the support are preferably made of a suitable refractory metal which willwithstand the filament temperatures, particularly tantalum which has the additional property of serving as a getter to absorb deleterious gases such as hydrogen and oxygen in the interior of the envelope,

In order to secure the wafer 12 to the filament 2 in a plane perpendicular to the axis of the filament, I preferably employ the constructiondisclosed and claimed in Patent 2,813,993, Fridrich, and applied by the method disclosed and claimed in Fridrich Patent 2,813,327. Accordingly, the wafer is formed from a strip of tantalum which is slitted at 17 (Fig. 3) so as to be slipped across and between adjacent turns of the filament coil 2 The wafer i2 is held and locked in place on the filament by a short collar-like portion composed of tabs or tongues t8 which project from one side of the wafer 21 short distance through the interior of the filament coil and engage with the inner side of the adjacent coil turn.

The collar portion 18 may be formed as disclosed in the aforesaid Patent 2,813,327, by piercing the Wafer 12, or the strip from which the wafer is subsequently punched, with a pointed piercing tool or mandrel inerted axially through the interiorof the filament coil while the wafer or strip is positioned in place on the coil, the piercing tool preferably having a pyramidal piercing end. The forming of the collar portion 18 by the piercing tool results in the formation of a circular aperture 19 bordered by the collar portion. The wafer 12 is thereby securely locked on the filament coil 2 in accurate relation to, and at the focus of, the elliptical portion 13 of its periphery, so that when it is inserted into the envelope l with its said peripheral portion 13 in engagement with the apex of the reflector section 6, the filament 2 is accordingly accurately located at the focus F1. The support 11 is completed by attaching the wire members 14-16 thereto, preferably by welding,

After the supports 11 have been attached to the filament 2, the lead wires 3 are attached to the ends of the filament, the assembly is threaded into the envelope 1 which is then purged of air and filled with an inert gas, and the ends of the envelope are heated and compressed about the lead Wires 3 to complete the lamp. The supports 11 are maintained securely on the filament in planes substantially perpendicular to the filament axis, with their elliptical peripheral portions 13 closely fitting the apex of the reflector portion 6 of the envelope by engagement of the ends of the fingers 14 with the shoulders 15 to hold the filament 2 along the focal line P1 of the reflector section.

A modified form of support is shown in Fig. 4 wherein the wafer portion 12a may be formed from a strip having a width corresponding to the straight sides and 21 so that the portion 13a of elliptical curvature, corresponding to the apex of the reflector section 6a of the envelope, is interrupted at the center by the side 21.. Also illustrated therein are the finger portions 14a without a connecting portion as shown at 16 in Figs. 2 and 3.

In the modification shown in Fig. 5, the finger por tions 14b of the support are made an integral part of, the wafer portion 12b which may have its entire outer periphery 13a of a contour corresponding to that of the entire inner surface of the reflector section 6b of the envelope.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A radiant energy device comprising an elongated tubular envelope of radiation-transmitting material having, in cross-section, a concave reflector section and an opposed flattened window section with internal shoulders defined by the junctures of said sections, a radiationemitting incandescible filament extending longitudinally of said envelope substantially at the focus of said reflector section, a layer of radiation-reflecting material on the surface of said reflector section, and a plurality of support members for said filament spaced apart along the interior of said envelope, each of said support members comprising a wafer portion having a modified portion of its periphery of a contour corresponding to that of the inner surface of the apex of said reflector section, said wafer being apertured to receive the filament substantially at the focus of its modified contour, means securing said wafer to the filament transversely thereof,

and brace means comprising finger members fixed to said disc and extending therefrom to respective ones of said internal shoulders to maintain said modified peripheral portion of the disc in engagement with the apex of said reflector section of the envelope.

2. A radiant energy device comprising an elongated tubular envelope of radiation-transmitting material having, in cross-section, a concave reflector section and an opposed flattened window section with internal shoulders defined by the junctures of said sections, a radiationemitting incandescible filament extending longitudinally of said envelope substantially at the focus of said reflector section, a layer of radiation-reflecting material on the surface of said reflector section, and a plurality of support members for said filament spaced apart along the interior of said envelope, each of said support members comprising a Wafer portion having a modified portion of its periphery of a contour corresponding to that of the inner surface or" the apex of said reflector section, said wafer being apertured to receive the filament substantially at the focus of its modified contour, means securing said wafer to the filament transversely thereof, and brace means comprising a wire member of modified U shape having a base portion extending between respective ones of said internal shoulders of the envelope and finger portions extending convergently therefrom and fixed to said wafer to maintain the modified peripheral portion of said wafer in engagement with the apex of the reflector section of the envelope.

3. A radiant energy device comprising an elongated tubular envelope of radiation-transmitting material having, in cross-section, a concave reflector section and an opposed flattened window section with internal shoulders defined by the junctures of said sections, a radiationemitting incandescible filament extending longitudinally of said envelope substantially at the focus of said reflector section, a layer of radiation-reflecting material on the surface of said reflector section, and a plurality of support members for said filament spaced apart along the interior of said envelope, each of said support members comprising a wafer having at least a portion of its periphery of a modified contour corresponding to that of the inner surface of at least the apex portion of said reflector section, said wafer being apertured to receive the filament substantially at the focus of its modified contour, means securing said wafer to the filament transversely thereof, said wafer having integral finger-like extensions extending to respective ones of said shoulders to maintain said modified peripheral portion thereof in engagement with the apex of said reflector section of the envelope.

References Cited in the file of this patent UNITED STATES PATENTS 2,135,480 Birdseye Nov. 8, 1938 2,137,732 Swanson Nov. 22, 1938 2,434,757 Cartun Ian. 20, 1948 2,813,993 Fridrich Nov. 19, 1957 

